Rikard Ambrus

Laser Speckle Contrast Imaging for Monitoring Changes in Microvascular Blood Flow

Background/Aims: Microvascular blood flow is essential for healing and predicts surgical outcome. The aim of the current study was to investigate the relation between fluxes measured with the laser speckle contrast imaging (LSCI) technique and changes in absolute blood flow. In addition, we studied the reproducibility of the LSCI technique when assessing the intra-abdominal microcirculation of the pig. Methods: During trial 1, a fish gill arch was mechanically perfused with heparinized fish blood under controlled stepwise-altered flow rates alongside mechanically induced movement artefacts. The microcirculation of the fish gill was simultaneously assessed with the LSCI technique. In trial 2, microcirculation was measured in the stomach, liver, and small intestine of 10 pigs by two observers. Results: A linear correlation was observed between flux and volumetric flow. During conditions of no volumetric flow, the high recording speed with the LSCI technique registered the movement artefacts as flow signals. The LSCI measurements showed good correlation and agreement between the two observers when assessing microcirculation in the stomach, liver, and small intestine (r2 = 0.857, 0.956, and 0.946; coefficients of variation = 6.0, 3.2, and 6.4%, respectively). Conclusion: Due to the non-contact and real-time assessment over large areas, LSCI is a promising technique for the intraoperative assessment of intra-abdominal microcirculation. A linear correlation between flux and volumetric flow was found, in accordance with previous experimental studies. However, movement artefacts affect flux measurements, and the choice of the sampling speed must be made with care, depending on the given setting.

Effect of propofol and remifentanil on cerebral perfusion and oxygenation in pigs: a systematic review

The objective of this review is to evaluate the existing literature with regard to the influence of propofol and remifentanil total intravenous anaesthesia (TIVA) on cerebral perfusion and oxygenation in healthy pigs. Anaesthesia has influence on cerebral haemodynamics and it is important not only in human but also in veterinary anaesthesia to preserve optimal regulation of cerebral haemodynamics. Propofol and remifentanil are widely used in neuroanaesthesia and are increasingly used in experimental animal studies. In translational models, the pig has advantages compared to small laboratory animals because of brain anatomy, metabolism, neurophysiological maturation, and cerebral haemodynamics. However, reported effects of propofol and remifentanil on cerebral perfusion and oxygenation in pigs have not been reviewed. An electronic search identified 99 articles in English. Title and abstract screening selected 29 articles for full-text evaluation of which 19 were excluded with reasons. Of the 10 peer-reviewed articles included for review, only three had propofol or remifentanil anaesthesia as the primary study objective and only two directly investigated the effect of anaesthesia on cerebral perfusion and oxygenation (CPO). The evidence evaluated in this systematic review is limited, not focused on propofol and remifentanil and possibly influenced by factors of potential importance for CPO assessment. In one study of healthy pigs, CPO measures were within normal ranges following propofol-remifentanil anaesthesia, and addition of a single remifentanil bolus did not affect regional cerebral oxygen saturation (rSO2). Even though the pool of evidence suggests that propofol and remifentanil alone or in combination have limited effects on CPO in healthy pigs, confirmative evidence is lacking.

A reduced gastric corpus microvascular blood flow during Ivor-Lewis esophagectomy detected by laser speckle contrast imaging technique

Abstract Background: Reduced microvascular blood flow is related to anastomotic insufficiency following esophagectomy, emphasizing a need for intraoperative monitoring of the microcirculation. This study evaluated if laser speckle contrast imaging (LSCI) was able to detect intraoperative changes in gastric microcirculation. Methods: Gastric microcirculation was assessed prior to and after reconstruction of gastric continuity in 25 consecutive patients operated for adenocarcinoma with open Ivor-Lewis esophagectomy while hemodynamic variables were recorded. Results: During upper laparotomy, microcirculation at the corpus decreased by 25% from baseline to mobilization of the stomach (p = .008) and decreased further (to a total decrease of 40%) following gastric pull to the thorax (p = .013). On the other hand, microcirculation at the antrum did not change significantly after gastric mobilization (p = .091). The decrease in corpus microcirculation took place unrelated to central cardiovascular variables. Conclusion: Using LSCI technique, we identified a reduced microcirculation at the corpus area during open Ivor-Lewis esophagectomy. LSCI provides an option for real-time assessment of gastric microcirculation and could form basis for intraoperative stabilization of the microcirculation.

The effect of glucagon-like peptide-1 and glucagon-like peptide-2 on microcirculation: a systematic review

GLP‐1 and GLP‐2 are gut‐derived hormones used in the treatment of diabetes type‐2 and short bowel syndrome, respectively. GLP‐1 attenuates insulin resistance and GLP‐2 reduces enterocyte apoptosis and enhances crypt cell proliferation in the small intestine. In addition, both hormones have vasoactive effects and may be useful in situations with impaired microcirculation. The aim of this systematic review was to provide an overview of the potential effects of GLP‐1 and GLP‐2 on microcirculation. A systematic search was performed independently by two authors in the following databases: PubMed, EMBASE, Cochrane library, Scopus, and Web of Science. Of 1111 screened papers, 20 studies were included in this review: 16 studies in animals, three in humans, and one in humans and rats. The studies were few and heterogeneous and had a high risk of bias. However, it seems that GLP‐1 regulates the pancreatic, skeletal, and cardiac muscle flow, indicating a role in the glucose homeostasis, while GLP‐2 acts primarily in the regulation of the microcirculation of the mid‐intestine. These findings may be useful in gastrointestinal surgery and in situations with impaired microcirculation of the gut.

POST-ENDOSCOPIC RETROGRADE CHOLANGIOPANCREATICOGRAPHY COMPLICATIONS IN LIVER TRANSPLANTED PATIENTS, A SINGLE-CENTER EXPERIENCE

Background: Complications in the biliary tract occur in 5%−30% after liver transplantation and the main part of the complications is successfully managed with endoscopic retrograde cholangiopancreaticography (ERCP). The incidence and risk factors for post-ERCP complications in liver transplantation patients are not well described. Our objective was to define the frequency of post-ERCP complications in liver transplantation patients at the Abdominal Center, Rigshospitalet, the only Liver Transplantation Center in Denmark. Methods: Retrospective study of all ERCPs performed in liver transplantation patients during a 9-year period. Results: A total of 292 ERCPs were included. Overall post-ERCP complications occurred in 24 procedures (8.2%): pancreatitis in 8 (2.7%), bleeding in 5 (1.7%), and cholangitis in 13 (4.5%) procedures. Simultaneous pancreatitis and cholangitis, and simultaneous bleeding and cholangitis occurred after two procedures, respectively. Multivariate analysis concerning overall complications identified biliary sphincterotomy (p = 0.006) and time since liver transplantation within 90 days postoperatively (p = 0.044) as risk factors for post-ERCP complications. Specifically concerning post-ERCP pancreatitis (PEP), it was found that pre-ERCP cholangitis was another independent risk factor for PEP (p = 0.026). Stent in the biliary tract prior to ERCP seemed to be protective (p = 0.041). Conclusions: Complications were of surprisingly mild degree. The rates of post-ERCP complications in our study were in line with previous studies with liver transplantation patients. Cholangitis prior to ERCP may be another risk factor for post-ERCP pancreatitis.

Laser Speckle Contrast Imaging to Evaluate Bowel Lesions in Neonates with NEC

Background  Necrotizing enterocolitis (NEC) is the most frequent surgical emergency in newborns. Intestinal ischemia is considered a factor that precedes the development of NEC lesions. Laser speckle contrast imaging (LSCI) can be used to assess tissue microcirculation. We evaluated if LSCI may help to detect intestinal regions with reduced microcirculation in NEC. Case Report  A male patient (gestational age, 26 [3/7] weeks; birth weight, 600 g) showed clinical signs of NEC 28 days after birth. X-ray revealed pneumatosis intestinalis and portal gas. Laparotomy showed NEC lesions with signs of transmural ischemia in the terminal ileum and cecum. Surgical resection lines (RLs) were marked, followed by LSCI measurements and resection of the bowel between the two RLs. Post hoc LSCI analyses were conducted on both sides of the proximal and distal RL. Low-flux values, indicating reduced microcirculation, were found in the macroscopically assessed necrotic bowel at the proximal RL, whereas higher flux values, indicating sufficient microcirculation, were found in the macroscopically assessed normal bowel. Discussion  This study is the first description of intra-abdominal use of LSCI to evaluate tissue microcirculation in relation to NEC lesions. LSCI could be a valuable tool to distinguish between ischemic and nonischemic bowel in neonates undergoing surgery for NEC.

Severe Postoperative Complications may be Related to Mesenteric Traction Syndrome during Open Esophagectomy

Background: During abdominal surgery, traction of the mesenterium provokes mesenteric traction syndrome, including hypotension, tachycardia, and flushing, along with an increase in plasma prostacyclin (PGI2). We evaluated whether postoperative complications are related to mesenteric traction syndrome during esophagectomy. Methods: Flushing, hemodynamic variables, and plasma 6-keto-PGF1α were recorded during the abdominal part of open (n = 25) and robotically assisted (n = 25) esophagectomy. Postoperative complications were also registered, according to the Clavien-Dindo classification. Results: Flushing appeared in 17 (open) and 5 (robotically assisted) surgical cases (p = 0.001). Mean arterial pressure was stable during both types of surgeries, but infusion of vasopressors during the first hour of open surgery was related to development of widespread (Grade II) flushing (p = 0.036). For patients who developed flushing, heart rate and plasma 6-keto-PGF1α also increased (p = 0.001 and p < 0.001, respectively). Furthermore, severe postoperative complications were related to Grade II flushing (p = 0.037). Conclusion: Mesenteric traction syndrome manifests more frequently during open than robotically assisted esophagectomy, and postoperative complications appear to be associated with severe mesenteric traction syndrome.

Robot-Assisted Hybrid Esophagectomy Is Associated with a Shorter Length of Stay Compared to Conventional Transthoracic Esophagectomy: A Retrospective Study

Aim To compare the peri- and postoperative data between a hybrid minimally invasive esophagectomy (HMIE) and the conventional Ivor Lewis esophagectomy. Methods Retrospective comparison of perioperative characteristics, postoperative complications, and survival between HMIE and Ivor Lewis esophagectomy. Results 216 patients were included, with 160 procedures performed with the conventional and 56 with the HMIE approach. Lower perioperative blood loss was found in the HMIE group (600 ml versus 200 ml, p < 0.001). Also, a higher median number of lymph nodes were harvested in the HMIE group (median 28) than in the conventional group (median 23) (p = 0.002). The median length of stay was longer in the conventional group compared to the HMIE group (11.5 days versus 10.0 days, p = 0.03). Patients in the HMIE group experienced fewer grade 2 or higher complications than the conventional group (39% versus 57%, p = 0.03). The rate of all pulmonary (51% versus 43%, p = 0.32) and severe pulmonary complications (38% versus 18%, p = 0.23) was not statistically different between the groups. Conclusions The HMIE was associated with lower intraoperative blood loss, a higher lymph node harvest, and a shorter hospital stay. However, the inborn limitations with the retrospective design stress a need for prospective randomized studies. Registration number is DRKS00013023.

Contents Vol. 56, 2016

I. Alwayn, Halifax D.K. Bartsch, Marburg C. Bassi, Verona W.O. Bechstein, Frankfurt am Main J.A. Bradley, Cambridge M. Cikirikcioglu, Geneva P.-A. Clavien, Zurich U. Dahmen, Jena R.W.F. de Bruin, Rotterdam S. Fichtner-Feigl, Regensburg H. Friess, Munich G. Galata, London D.J. Gouma, Hilversum J.K. Habermann, Lübeck M. Heberer, Basel M. Heger, Amsterdam T. Hubert, Lille W.R. Jarnagin, New York, N.Y. J.C. Kalff, Bonn M.W. Laschke, Homburg/Saar H.-A. Lehr, Friedrichshafen C.M. Malata, Cambridge T. Minor, Bonn M. Morino, Torino J. Pirenne, Leuven A. Schachtrupp, Melsungen T. Schmitz-Rixen, Frankfurt a.M. R. Schramm, Munich L. Steinstraesser, Oldenburg A. Szijártó, Budapest R.H. Tolba, Aachen M. van Griensven, Munich T.M. van Gulik, Amsterdam M.A. Venermo, Helsinki M.H. Wilhelmi, Hannover D.C. Winter, Dublin Y. Yamamoto, Akita Clinical and Experimental Surgery